The measurement of blood glucose by diabetic patients has traditionally required the drawing of a blood sample for in vitro analysis. The blood sampling is usually drawn by the patient as a finger puncture. The need to draw blood for analysis is undesirable for a number of reasons, including discomfort to the patient, the time required for medical personal to draw and handle the samples, the high cost of testing supplies, and the potential risk of spread of disease through punctures of the skin.
Many of the estimated three million Type 1 (juvenile) diabetics in the United States are asked to test their blood glucose six times or more per day in order to adjust their insulin doses for tighter control of their blood glucose. As a result of the discomfort, many of these patients do not test as often as is recommended by their physician, with the consequence of poor blood glucose control. This poor control has been shown to result in increased complications from this disease. Among these complications are blindness, heart disease, kidney disease, ischemic limb disease, and stroke. In addition, there is recent evidence that Type 2 (adult-onset) diabetics (numbering over 10 million in the United States) may reduce their incidence of diabetes-related complications by more tightly controlling their blood glucose. Accordingly, these patients may be asked to test their blood glucose as often as the Type 1 diabetic patients.
It would thus be desirable to obtain fast and reliable measurements of blood glucose concentrations through simple, non-invasive testing. Prior efforts have been unsuccessful in the quest for a sufficiently accurate, non-invasive blood glucose measurement. Many of these efforts have involved the passage of light waves through solid tissues such as the fingertip or the ear lobe, with subsequent measurement of the molecular absorption spectrum of glucose. These efforts have been largely unsuccessful primarily due to the variability of absorption and scatter of the electromagnetic energy in the tissues. Other groups have attempted blood glucose measurements in body fluids such as the anterior chamber, tears, and interstitial fluids. To date, these efforts have met with only limited success.
Thus a need exists for a simple, painless, non-invasive method for determining the concentration of glucose in a patient's blood.